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The Break Latlie.                           159

The fast head-stock B has a large 'Cylindrical bearing at c, with
adjustable cap, while the pressure of the surfacing cut is taken by
the collars of the thrust bearing D. The face plate requires no
further description than that given for Fig. 143, except to say
that the jaw screws themselves take the grip, and that the jaw
boxes may be unbolted and the work attached directly to the
plate. The back of the plate has an annular spur wheel, driven
by a system of * treble gear/ We may turn the mandrel through
the four wheels E F G H in simple back gear; or directly, bolting H
to the cone pulley, and throwing out F and G by turning eccentric
bushes ; but if a slower speed be desired G is slid to the right, E
and F kept in gear, while wheel K and pinion M, keyed to the
'third shaft L, are moved to engage respectively with pinion j and
wheel N on face plate.

We have, therefore, three alternatives :—Direct driving without
gear; double-purchase gear, E into F, and G into H ; or treble-
purchase gear, E into F, j into K, and M into N. The last is
only required for large diameters of work.

The leading screw, lying within the lathe-bed at A, is driven,
by change wheels p, through shaft Q, and wheels R R at the right
end of bed. By removing the change wheels, the backshafts may
be put in gear, the power being taken from the belt x, passing
thence to the worm shaft u by spur wheels, and across to the rack
pinion, as in the previous lathe. The handle v will pull the lever
w, and clamp the leading screw nuts, while the traversing
motion may be reversed at x. The slide rest has the same
motions as have been described for Plate V., and the loose head-
stock needs no further description.

This machine tfs used:—(i) As a screw-cutting lathe with or
without gap; (2) as a face lathe. For the first the gap may be
varied by loosening the bolts which hold the bed Y to the founda-
tion z ] and by then applying a lever to boss K to turn a rack
pinion ^ £, so bring the bed nearer the face plate, the standard
d being also removed. The work would be supported between
the lathe eentres, and driven by a bolt in the face plate, or by
small drivers as usual

As a Face Lathe, the gap is widened; and* the upper parts
efg of the slide rest being removed, they are bolted on the